A semiconductor light-emitting element such as a light emitting diode (LED) or a laser diode (LD), which can be used as a light source or the like for a projection-type display device, emits light when electricity flows and also generates heat upon emission of the light. When the temperature of the semiconductor light-emitting element increases, the luminous efficiency decreases and a sufficient amount of light cannot be obtained. In addition, the lifetime of the semiconductor light-emitting element becomes shorter. In the projection-type display device, in order to stably exhibit optical performance and to continuously maintain the performance, it is necessary to cool the semiconductor light-emitting element and to control the temperature to a predetermined level or less while in use.
Patent Literature 1 (JP2015-130461A) discloses a technique serving as a cooling system of a semiconductor light-emitting element, in which an installation member on which a laser diode is installed is provided in the internal space of a hermetically sealed housing, a coolant flow path is provided in the installation member, and an inlet end and an outlet end of the coolant flow path are used as an external space of the hermetically sealed housing.